1. Field of the Invention
The invention relates to a heat exchanger tube for transferring heat from a flowing medium to another flowing medium, which tube is composed of a metal outer tube and a metal inner tube, whose facing surfaces are provided with substantially complementary profiles and rigidly abut against each other to form at least one longitudinal channel for leak detection extending between the outer tube and the inner tube. The invention also relates to a method of manufacturing such heat exchanger tube.
2. Background Art
Such heat exchanger tube is known from GB-A-2 109 913. The outer and inner tubes which together form the double-walled heat exchanger tube are fed as smooth tubes to a deforming apparatus, which initially reduces the tubes in diameter, with fins being formed on the outer tube. At the end of the deforming process, the parts of the outer tube located between the fins, together with corresponding parts of the inner tube, are pressed inwards, so that a corrugated, double-walled tube is created, with a leak-detection channel remaining each time between two inwardly pressed corrugated parts of the double-walled tube.
However, this heat exchanger tube does not guarantee that in the case of substantial temperature differences and fluctuations between the media on either side of the double-walled heat exchanger tube or in one of the media, the facial contact between the inner and the outer tube, which is to provide the desired, proper heat transfer, is maintained in the manner required. Tests have shown that as a consequence of the expansion and/or shrinking movements of the inner and/or outer tube, a slowly progressing splitting occurs between the two tubes, which gradually reduces the heat transfer capacity to a minimum.